基于MAP沉淀法的黑水中氮、磷元素回收技术

The Recycling technology of nitrogen and phosphorus in black water by MAP precipitation

【目的】黑水(粪污废水)污染物质量浓度高,较难处理,并且容易导致水体富营养化,同时黑水中氮磷元素含量高,具有很高的资源回收和利用价值。对体积小且氮、磷质量浓度高的黑水单独收集处理,更容易实现资源化利用。目前对氮磷资源的回收处理主要集中在养殖废水领域,鲜少有对居民黑水进行单独回收氮磷资源的研究,且多数研究处于实验室规模或中试规模,如何在无害化处理黑水的同时,尽可能回收黑水中可再生资源是我们研究的重点。【方法】本研究利用磷酸铵镁沉淀法回收黑水中氮磷元素,通过单因素试验、正交试验比选、吸附材料试验、扫面电镜和XRD图谱分析。【结果】1)最佳的回收工艺条件为Mg∶N∶P=1.5∶1∶1,pH值9.5,磷初始质量浓度200 mg·L^(-1),最佳工艺条件下氨氮回收率为69.14%,磷回收率94.04%;各因子重要程度排序为:磷初始质量浓度>氮磷比>pH值>镁磷比。2)最佳吸附材料为钙基膨润土,静态吸附试验后氨氮和磷的回收率分别为84.37%和98.68%。3)磷酸铵镁沉淀法可有效回收黑水中的高质量浓度氮磷,通过XRD图谱分析可知所得鸟粪石纯度很高,主要成分为MgNH_(4)PO_(4)·6H_(2)O。【结论】采用磷酸铵镁沉淀法与膨润土吸附相结合的方式,氨氮的回收率从最佳试验条件下的69.14%提升到了84.37%,磷的回收率从94.04%升至98.68%。与传统的磷酸铵镁沉淀法或单一的膨润土吸附法相比,该方法能在保证磷的高回收率不变的情况下,提高氨氮的回收率。

【Objective】Black water(namely fecal wastewater)is high concentration of contamination and difficult to treat.Due to the high proportion of N and P in black water,easily leads to eutrophication.But the high proportion of N and P also make black water have high resource recovery and utilization value.Separately collect and treat small-scale black water and the high nitrogen and phosphorus concentrations can be easier to realize resource utilization.Currently,the the recovery of nitrogen and phosphorus is mainly focused on breeding wastewater,while rarely study for residents’black water.In addition,the majority of these researches are on the scale of laboratory or pilot-scale.Therefore how to recycle the black water’s renewable resources as much as possible while treating the black water in a harmless manner is the focus of our research.【Method】This research adopts magnesium ammonium phosphate precipitation method to recover the nitrogen and phosphorus from black water.Obtaining the following results by single factor experiment,orthogonal experiment comparison,adsorption material experiment,scanning electron microscope and XRD pattern analysis.【Result】1)Under the optimum technological conditions when Mg∶N∶P=1.5∶1∶1,pH=9.5,initial phosphorus concentration is 200 mg/L,the recovery rate of ammonia and nitrogen and phosphorus are 69.14%and 94.04%;2)Ca-bentonite is the the optimal adsorption material,and the recovery rates of ammonia-nitrogen and phosphorus are 84.37%and 98.68%respectively after static adsorption experiment;3)The XRD pattern analysis shows that the obtained struvite has a high purity,and the main component is MgNH_(4)PO_(4)·6H_(2)O,which proved that the magnesium ammonium phosphate precipitation method can effectively recycle the high concentration of nitrogen and phosphorus in the black water.【Conclusion】Adopting the combination of magnesium ammonium phosphate precipitation and bentonite adsorption with the optimum experimental conditions,the recovery rate of ammonia nitrogen increased from 69.14%to 84.37%,and phosphorus increased from 94.04%to 98.68%.Compared with the conventional magnesium ammonium phosphate precipitation method or the single bentonite adsorption method,this method can improve the recovery rate of ammonia nitrogen while ensuring the high recovery rate of phosphorus.